1. Field of the Invention
The invention relates to a cell for performing optical measurements in an automatic analyzer and more particularly a single cell for an analyzer for chemical analyses.
2. Description
Cells for performing optical measurements are conventionally charged with samples and reagents in the analyzer, and electro-optical analysis is carried out on the mixture of sample and reagent contained in the cell.
Analyzers are known which use single reaction cells, also called measuring cells which are placed on a suitable carrier in the analyzer by a mechanical, automatically-controlled transport device and are removed therefrom after use. In these analyzers each cell remains on the cell carrier for the entire period of the analysis. Transport of each cell to the cell carrier and its removal from the carrier therefore take place only once. The risk of a cell being lost during transport is therefore relatively low.
In modern analyzers, in which the attempt is made to achieve a high number of measurements per unit of time, in correspondingly short cycle times, it is desirable to carry out some of the steps of the analysis process (e.g., the addition of reagents to individual cells, carrying out mixing movements of the cells, and so on) outside the cell carrier, and to use the cell carrier predominantly for performing optical measurements on the mixtures of sample and reagent in the cells. For this purpose, the transport of each cell to the cell carrier and its removal from the carrier must be carried out a number of times. Also, the transport system must allow each cell to be transported between the cell carrier and different processing stations. In addition, some analysis systems operate with rotatable cell carriers. It thus may be desirable to transport the cells even when the cell carrier is rotating. Consequently, the risk of a cell going astray with such a flexible and repeated transport system is correspondingly higher.
In many applications, the loss of a cell in the analyzer system is unacceptable. In otherwise extensively automated analyzers, any possibility of cell losses during their transport would make it necessary to at least visually monitor the transport of the cells during the operation of the analyzer. This is practically impossible.